Do you envy Gentoo users their tuning? Debian packages are mostly shipped only with a basic optimization (-O2) and for more generic CPUs. How about fine tuning for your CPU?

I tried apt-build which is targeted for the optimized recompilation but it is supported by a very few packages. Following steps did the job e.g. for clang/llvm. First install required stuff:

• Basic packages:

  sudo apt-get install fakeroot dpkg-dev build-essential

• Dependencies and sources:

  apt-get build-dep clang llvm-3.1
  apt-get source clang llvm-3.1

Now you have to modify compilation flags. They are often stored in debian/rules or debian/rules.d/vars.mk. Find these files in the unpacked sources and locate line with “opt_flags = -g -O2“. This holds options for the configure script. Different packages might have different entry, look for CFLAGS, CXXFLAGS, … Replace the options e.g. with “-O3 -march=native” and carry on with the compilation:

• Go to the source directory:

  cd llvm-3.1-3.1

• Build:

  dpkg-buildpackage -rfakeroot -us -uc

• Install the packages:

  cd ..
  sudo dpkg -i llvm*.deb clang*.deb

Speedup is not very interesting (approximately 5 % in the case of clang/llvm) but why not try.